I have some questions too, if that's okay..
Regarding the use of an underquilt in - temps.. Is the efficiency of the quilt dependent on the heat generated by the body to warm it up, thereby acting as an insulator? that's my understanding. But if you put a ccf mat between the user and the quilt, isn't that going to stop the bodies heat from getting to the quilt? making it pretty pointless using it?
I've not used a hammock in freezing temps, I intend to, at some stage though. This is something I've been trying to get my head around for a while. I'm trying to gage what types of temps my current gear will keep me toasty in if I combine them to their best configuration.